Resistor element



Dec. 14, 1937.

E. E. ARNOLD RES I STOR ELEMENT Filed June 15, 1935 INVENTOR 20 50102725' Arnold ATToN EY Patented Dec. 14, 1937 UNITED STATES PATENT OFFICE 2,1o2.3o2 RESISTOR ELEMENT Edwin E. Arnold, Pittsburgh, Pa.,

Westinghouse Electri assignor to c & Manufacturing Company, East Pittsburgh, Pa, a corporation'oi' Pennsylvania Application June 15, 1935, Serial No.. 26,848

6 Claims.

fore frequently been due to irregular contact be-' tween the resistor element and the surrounding insulating material. Such irregularity is likely to produce overheating of the element at spots, which materially lessens the life of the element.

It is an object of this invention to produce a resistor element which can be more readily and securely bonded with the insulating material in the heater element. I

It is a further object of this invention to pro duce a resistor element which will be inexpensive to manufacture, can readily be made with automatic machinery and will require no special skill to unite it, with the insulating material of the heater element.

It is a further object ofthis invention to provide a resistor element which shall resist motion through the resistor material in any direction with a greater resistance than would be offered by only the edges of a ribbon of the same area as the resistor element.

Other bbjects of my invention and details of the construction and of the method used to construct the element will be apparent from the following detailed description and the accompany-v ing drawing, in which: i Figure 1 is a face view of one form of the resistor element, the left-hand portion being shown inan early stage of its manufacture;

Fig.v 2 is a diagrammatic section showing the plunger and die used in making that form of the" resistor element shown in Fig. 1;

Fig. 3 is a similar view showing the plunger at the completion of its stroke;

Fig. 4 is a face view similar to Fig-p1 of an 5 alternative form of a resistor element;

Fig. 5 is a view similar to Fig. 2, illustrating the die andplunger used for the manufacture of that form of the resistor shown in Fig. 4.

Fig. 6 is a view similar to Fig. 3, showing the plunger at the completion of its stroke; and

Fig. 7 is a view of a mechanism for making that form of the resistor element shown in Fig. 4.

The resistor element is made of a strip I of sheet metal having suflicient resistance to be suitable for an electric heater. At each end of the strip I, a flat portion 2 is provided which may be equipped with holes, projections or any other for providing terminal connec- As my invention is not related to these provisions, they are not illustrated or further de- 5 scribed.

The main portion of the strip is slitted' alternately from opposite edges to constitute a zigzag The uniting portions, such as 6, are fiat with the plane of the strip l.

The transverse portions 5 are twisted so that they occupy a position at right angles to said plane. The twists illustrated at 1 and 8 at optransverse members at right angles to that plane. It can be stretched or twisted, or, to-a lesser degree, compressed without distortion of the metal 30 itself to any significant extent. It thus adapts itself readily to any deformation required in in- The effective thickness of the resistor element 0 in the central part is the width of the transverse portions. Although they do not completely occupy all the space in this thickness, the space needed to accommodate the resistor element is of this thickness. The portions 6 on the other hand form when considered all together a pair of margins forthe element of no more thickness than the metal itself.

In the manufacture of that form of the resistor element shown lnFig. 1, it is preferably moved'step by step along a rack composed of supporting teeth It! and a uniting structure. Cooperating with the rack is a plunger equipped with teeth It and a uniting body 12. The strip I is in position for the die to woik when each slit, such each strip. The teeth as d, is positioned in the middlebithe face of a supporting tooth iii and the slots from the opposite edge of the strip I, such as the slot}, are each midway between two supporting teeth As the plunger descends, each edge by a tooth ii of the plunger and in an upward direction on the opposite edge by a sup porting tooth ill. Each strip 5 is thus twisted, the sense of the twist being opposite for any two adjacent strips. The strip I may be stepped forward between each successive stroke of the die until the whole .length of the strip has been acted upon or a plunger and a supporting rack'of sufiicient length to act upon the whole strip at once may be provided and the resistor element finished in one stroke. I

. In making the form of resistor strip illustrated inFig. 4, a rack having supporting teeth l6 and a connecting portion as illustrated in Fig. 5 is used. The coacting teeth l5, a corner ll of each tooth being beveled. The operation of this die is similar to that illustrated in Figs. 2 and 3. The strip i, when it is in position for the die to work, is supported upon the teeth I6 so that the faces of these teeth contact the strips 5 adjacent to but not at an edge,

the supported edge being on the same side for IS contact the middle of the unsupportedportion of the strips and as the plunger descends all of the strips are twisted in the same sense. As the twisting occurs, the edge of the strip nearest the supporting face of the tooth l6 rises, and in order to provide for this motion of said edge, the corners ll of the plunger teeth have been beveled, as shown.

Another form of mechanism \transverse strips of the resistor i is illustrated in Fig. '7. It comprises a supporting rack havin supporting teeth 20 and a connecting body. Co-

' operating with this rack is a pinion Zl. In the the right.

operation of this mechanism, if the pinion rotates in the direction indicated by the curved arrow, the rack Zll and the strip I will be moved toward the left or the pinion will be moved toward If the machine designer so desires, he may provide for both of these elements to move. As this motion occurs, the teeth of the pinion contact with the transverse ember 5. As illustrated at 22, the side face of ooth contacts the transverse portion 5 being twisted throughout nearly the full width of said portion.

As the pinion continues to rotate, the transverse the lower part of it contacts with the side face of the supporting tooth 20 as illustrated at 23. As

the motion continues beyond this point, a shoulder 24 of the tooth drags across a portion of the face of the twisted portion. 1 i It will be observed that in this operation of the mechanism, there is very little inefiective contact, between the teeth of the pinion and the strips. It is possible to twist the strips by the mechanismillustrated in Fig; 7 operating in the opposite sense, but when this is done, the bending action of the teeth of the pinion is performed almost entirely by the shoulders of the teeth and the result is poor efiiciency. The preferred direction for the travel of the rack and the strip transverse member 5 is acted upon in a downward direction on oneplunger is equipped with.

for twisting the is such that the supported edges of the transverse portions 5 are the forward-edges.

I do 'not desire to be limited ments made by the .mechanical methods described herein, since the resistor elements will possess .the same desirable qualities if made by any suit able mechanical method.

I claim as my invention: 1

1. Aconductive resistor element comprising a sinuous ribbon of sheet'metal having transverse portions each in a plane normal to the plane of the element, margin portions joining each pair of successive transverse portions the margin portions being in a plane parallel to the plane of the element, said transverse portions having tor sionally twisted portions, one at each end of each transverse portion uniting it to the respective margin portions.

conductive resistor element having two series oi marginal portions, the members of each series being spaced away from the adjacent members of that series and all members of both series being in one substantially flat surface, said resistor element also having connecting members each joining one of said marginal portions in one series to the succeeding member of the otherto resistor eleseries, said connecting members being so tor sionally twisted'that, except at their junction with the marginal portions they are at an angle to said flat surface.

3. A conductive resistor element having-two series of marginal portions, the members of each series being spaced away from the adjacent members of that series and all members of both series being in one substantially flat surface, said resistor element also having connecting members each joining one of said. marginal portions in one series to the succeeding member of the other series, said connecting members being so torsionally twisted that, except at this junction with the marginal portions they are at an angle to said flat surface, the twist being in opposite senses in the twisted portions of eachone of the connecting members.

4. A resistor element in the form of a ribbon extending zig-zag from side to side of the element and having two twisted portions ineach traverse from one side to the other, said twisted portions being near the sides of the resistor element and the portion of the ribbon between them being untwisted.

5; A resistor element in the form of a ribboh extending zig-zag from side to side of the element and having two twisted portions in each traverse from one side to the other, said twisted portions being near the sides of the resistor and the portion of the'ribbon between them'being untwisted, the portions of the ribbon between one traverse and the next also being untwisted.

6. A resistor element in the form of a ribbon extending zig-zag from side to side of the element and having two twisted portionsin each traverse from one side to the other, said twistedportions being near the sides of the resistor and the portion of the ribbon between them being untwisted, the portions of the ribbon between one traverse and the next also being untwisted, and in a plane at an angle to the first-named untwisted portion.

' EDWIN E. ARNOLD. 

